Connector



Oct. 29. 1940. LG. B-OOMSMA I 2,219,913

CONNECTOR Filed May s, 195::

. 3mm 10103" a floomsma Lm\\\\ x Patented a. 29, 1940 UNITED STATES PATENT OFFICE.

CONNECTOR Louis G. Boomsma, New York, N. Y. Application May 3, 1938, Serial No. 205,805 2 Claims: (01. 173-328) This invention relates to an improved electrical connecting device which device is of generally Wide applicability in making electrical contacts and is peculiarly adapted for coupling an elec- 5 trode bearing end of a gas filled tube constituting part of a luminous display to a source of electric current to cause the gas within the tube to become luminous. The source of current in such specific use may be either a corresponding electrode bearing end-0f a similar gas filled tube or an initial source for the complete display.

Due to the widespread use of luminous tube displays of the type comprising glass tubes filled with a gas which will emit a characteristic light of substantial intensity when a difference in electric potential is applied to electrodes sealed in the ends of the tubes, there has been great demand for a suitable device which could be used to establish electric connection between such electrodes and a source of electrical energy. Since it is common practice to remove the tubes from a display which has served its purpose and adapt them without major alteration to use in another display, such device must be capable of attachment and removal without damage to the tubes.

Other primary considerations to be observed are the effective insulation of the connection to avoid 35 be borne in mind that luminous displays of the type described normally operate over a rather wide range of temperatures resulting in expansion; contraction, and some distortion of elements.

40 In view of the use to which luminous tubes are put, it is a prime essential that any connecting device harmonize with the appearance of the whole and that it bev as free as possible of unsightly protuberances, taped joints, and the like- 45 At the present time, it is common practice to mount an annular rubber member near the end of each of two tubes to be joined. Wires sealed in the ends of the glass tubes extend from the electrodes to a brass connector external to the 50 tubes and to which the wire from each tube is attached as by a bolt. The connecting assembly is enclosed in a glass tube of larger diameter than the tubes forming the display, which larger tube is maintained in position by the rubber mem- 55 bers noted. The joints are frequently taped to insure against displacement of the insulating tube.

It has been suggested that the connection be made by a'metallic spring maintained in position in a glass tube oflarger diameter than the s luminous tubes by a cotter pin passed through the connecting tube, said spring having concave members welded to each end. I When the ends of two tubes bearing electrodes sealed in the glass are inserted into opposite ends of the larger tube, 10 the spring acts as an electric conducting medium to maintain contact with each .tube. It has been observed that such construction is unsuitable for general application and to my knowledge it has not been accepted by the art to any material ex- 15 tent. Among the major'objections to this expedient is thatit involves use of a conducting member in contact with conducting spring which has portions outside the insulating tubes, thereby permitting accidental grounding of the circuit go with resultant loss of electricity, danger or fire, and possibility that human life or well being will be-aiiected by contact with the exposed ends of the cotter pin. Further disadvantages obviously follow weakening of the insulating tube by form- :5

ing holes through the walls thereof.

The present invention provides a means for connecting the ends of luminous tubes to a source -of electrical energy, either an outlet or the end of another tube in the series constituting the com- .plete display rapidly and easily while avoiding the disadvantages of the prior art.

It is an object of my invention to provide such a connecting device of improved design compris-. ing a connecting tube which will provide positive insulation of conducting elements in a structure of pleasing appearance. In its preferred embodiment my invention 'contemplates theprovision of a connector for luminous tube displays comprising a tube of greater 40 diameter than the display tubes having a helical spring disposed therein and maintained in operative position by an integral part of said tube.

Otherobjects and advantages of the improved connecting device will be apparent upon consideration of the following detailed description in connection with the accompanying drawing wherein:

Fig. -1 is a sectional view of the connecting device in operative position.

Fig. 2 shows the assembly of Fig. 1 in another operative position; and

Fig. 3 is a sectional view of a modified form of the novel insulating tube.

One embodiment of the present invention is,

illustrated by the drawing as a connection between adjacent ends of successive gas filled tubes I and I I adapted to be rendered luminous by the passage therethrough 01' an electric current; the said tubes forming part of a display assembly. The end of each tube is fitted with an electrode I2 and a metallic cap I3 fastened to the end of the electrode wire and over the end 01' the tube. The ends of the tubes are shown as bent in the manner which has become general practice in the art at a point of connection between two tubes; but it is to be understood that the invention isnot limited to tubes having their end portions bent in the manner shown. The tube I4 is formed of any suitable non-conducting material such as glass and has an inside diameter somewhat greater than the outside diameter oi the electrode and of luminous gas filled tubes I0 and II. ing material such as a copper alloy or other resilientconductor of electricity is maintained in its preferred position in tube I4 by a constricted portion I6 01 the said tube near the mid point thereof. In the preferred embodiment the diameter of the spring I5 is but slightly less than the inside diameter of tube II for the greater portion of its length, the two ends of the springs being in the nature of a spiral to give a good contact with the metallic caps I3.

The nature of the material of which tube I4 is made is not critical so long as that material is a non-conductor of electricity and possesses a reasonable degree of mechanical strength. Metal tubes lined with non-conducting material are highly satisfactory alternatives in some cases. For example, the tube may be cast from a resinous substance, either natural or synthetic. The methacrylic polymerization products may be used to make transparent tubes or an opaque resin as phenol-formaldehyde condensation products may be employed. The nature and manner of casting resins is well known and their formation into tubes for the purpose of this invention involves no new technique.v

With cast materials, the form of tube ll shown in Fig. 3 may be used to advantage by casting the constricted portion I6 integral with a tube hav-' ing a straight exterior wall. Although this form may also be used with glass, it is preferred to make glass tubes in the manner illustrated by Figs. 1 and 2 in view of the fact that this formation is easily accomplished by heating a glass tube of the proper diameter in the mid section until it becomes somewhat plastic and then forming the constriction by drawing or other suitable procedure.

The constriction of the internal bore of the tube I4 may also be produced, if desired, by the insertion of a ring of material, conducting or non-conducting, or by the provision oi ridges or spurs within'the tube at the point where constriction is found to be advisable. For easy handling such ridges or spurs should be formed integral with the tube wall as by casting or by tool work while the tube is in a'plastic state.

It will be clear that the tube I4 may be made opaque by reason of the material used or by costing the exterior of a transparent tube with an opaque paint or the like. Such opaque tubes A coiled spring ii of conductmay be used to mask a considerable portion of the ends of the luminous tubes Ill and II as will be apparent to those skilled in the art.

The extreme flexibility in operation of the present conneting device is illustrated by comparison of Figs. 1 and 2. The spring may be compressed by deep insertion of the ends of tubes I 0 and I I to a point where the actual gap between the metallic caps I3 is about one quarter of an inch and yet the spring maintains an effective electrical connection between the caps when spaced as much as three and one-half inches when using a connector of the dimensions I have found to be suitable for most commercial installations. It is, of course, possible to make a connector effective over a much wider range and such modification is contemplated within the scope of this invention.

It should be further noted that the connector may be modified by making itv angular in general outline, which will permit the use of straight tubes with an angular connector, according to my invention, instead of a bend in a longer single tube, or by the provision of positive frictional engaging members, .as a small rubber gasket adapted to lie between the interior of tube I4 and the exterior of tube I0 or II, without departing from the spirit of this invention. These and other modifications as attachment of plates. balls and the like to the ends of spring I5 for making contact with the metallic caps I3 will be apparent to those employing'the novel connecting device and it is intended that the above description shall be taken as illustrative only of the invention which is defined in the following claims.

I claim:

1. An electrical connecting device comprising a hollow tube of non-conducting material having a substantially constant internal diameter throughout the greater portion of its length, nonconducting means intermediate the ends of the tube and integral therewith to reduce the internal diameter thereof and a metallic coiled spring disposed within said tube, said spring having a diameter throughout the greater portion of its length less than the larger internal diameter of said tube and greater than the internal diameter of said tube at the position of said means, the diameter of the spring being reduced intermediate its ends and adjacent said means to form shoulders adapted to resiliently engage said means, whereby the spring is maintained in operative position to make positive contact with conducting elements inserted into the ends of said tube.

2. An electrical connecting device for gaseous electrical discharge tubes which comprises a hollow tube of non-conducting material, a metallic coiled spring within said tube, the tube having a portion thereof of sharply varied transverse dimensions to provide shoulders on the inside surface of the tube and the spring having at least one part intermediate the ends thereof of transverse dimensions adapted to resiliently engage said shoulders whereby to hold the spring against bodily removal from the tubes, but the ends of the springs being free for compression and reexpansion within the tube.

LOUIS G. BOOMSMA. 

